I have a doubt, some jQuery methods expect a function as a parameter, but to work they should receive an inner function as a parameter instead of a function directly, as in the example below:
$("a").on("click", function() { retornaNada(); });
instead of
$("a").on("click", retornaNada());
Consider retornaNada() as a function of any type without a code body. Why can not we pass the function directly?
Methods that expect a function expect a reference function. For example:
$("a").on("click", retornaNada);
This is advantageous if you want to use the same function as event handler in more than one place. For example:
$("a").on("click", retornaNada);
$("span").on("click", retornaNada);
Passing anonymous functions would require two different functions.
Now notice that what you did was:
$("a").on("click", retornaNada());
// ----------^^
You called the function, and actually passed the return value as the handler. As retornaNada does not return anything, including the parentheses means the same as:
$("a").on("click", undefined);
So it does not work.
You can only send the function name. for example: You declare the function that will handle the event before:
function meuOnClick() {
...
}
And then it makes your jquery point to it:
$("a").on("click", meuOnClick);
Note that it is without parentheses. However, this is kinda bad, because you will not be able to use the jquery selectors, such as $ (this). The normal thing is to use an anonymous function.